[Stoves] Reports from ETHOS meetings: the future of TLUD research

Julien Winter winter.julien at gmail.com
Wed Jan 28 11:45:15 CST 2015


I was at ETHOS this year presenting some of my basic investigations of TLUD
function, and I will circulate a copy of my presentation shortly.  Kirk
Harris presented his fascinating burner design.

For me, one of the most interesting things at ETHOS was not what was
presented, but what is coming.  The Colorado State University has received
a very large grant from the US Department of Energy to improve our
scientific understanding of natural draft TLUDs.  This year at ETHOS, they
didn't present any results, but they described the laboratory equipment
that they have assembled.  They will be able to measure the flow rates of
primary and secondary air, fuel bed and gas flame temperatures, gas flame
structure, the composition of the pyrogas as it exists the fuel bed, and
exhaust gas and particulate emissions.  They are able to test a variety of
gas burners to increase clean-burning --- the most pressing issue today.
Knowledge gained on pyrolysis, combustion, and gas flows will be
systematized into computer simulation models.

This work is much needed.  Since the early 1980s, forced draft systems have
been extensively studied, however, except for a couple of recent papers,
natural draft systems, have not been studied at all.  Research on forced
draft has provided us with some very important information, but it doesn't
extrapolate sufficiently well to natural draft systems.    Natural draft
systems different from forced draft systems, in three basic ways: (1) they
operate at lower gas velocities, near atmospheric pressure, (2) operational
temperatures cover a lower range, and (3) and their processes, are
interconnected through feed-back mechanisms.  We have to understand how
these feedbacks work for designing ND-TLUD stoves.  For example, how does
the size and shape of the pyrogas flame affect draft for primary air -->
gasification rate --> size and shape of the pyrogas flame --> ...

It will be interesting to see what the workers at Colorado State University
come up with.  I expect they will be able to tell us what the control or
limiting points are in the TLUD reaction, such as resistance to gas flow in
the fuel bed, or heat production at the pyrolytic front.  They should be
able to tell us how the thickness and temperature of the char layer above
the pyrolytic front changes the composition of pyrogas rising through it.
They should be able to tell us how the composition of pyrogas changes over
a turndown curve.   Most importantly, I hope they will provide guidelines
for designing burners, reasons for why one thing works and not another, and
a computer program to simulate design decisions.

The results from the Colorado State University lab can't come too soon.

Cheers,
Julien.

---------------------


-- 
Julien Winter
Cobourg, ON, CANADA
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20150128/bc967041/attachment.html>


More information about the Stoves mailing list